It has become very popular to provide a hand-held device with a camera function, and various anti-shake lens focusing modules have also been developed for incorporating into many advanced hand-held devices in recent years. Lens focusing modules with anti-shake function have been disclosed in many prior art patents and new patent applications, such as U.S. Pat. No. 7,881,598 entitled “Anti-shake Auto-focus Modular Structure” granted to the same applicant; U.S. patent application Ser. No. 12/717,596 entitled “Anti-shake Structure for Auto-focus Module” filed by the same applicant, and U.S. patent application Ser. No. 12/910,519 entitled “Tilt-type Anti-shake Compensation Structure for Auto-focus Module” also filed by the same applicant.
Whenever a lens auto-focus structure moves a lens to a desired position for focusing, the lens auto-focus structure will vibrate slightly for a period of time before it gradually returns to a still state again. The time period needed for the lens auto-focus structure to change from the moving state to the still state is referred to as “dynamic response time”. U.S. Pat. No. 7,590,342 entitled “Method and Structure for Suppressing Response Time of Lens Focusing Structure” granted to the same applicant discloses technical means for suppressing the dynamic response time of a lens focusing module vibrating in the process of focusing.
Similarly, an anti-shake structure will also vibrate slightly when it moves to correct any image displacement. Since the lens focusing and the image correction occur at the same time in a camera when using the camera to take a picture, it is possible mutual resonance occurs in an anti-shake lens focusing module when the lens focusing structure and the anti-shake structure thereof vibrate simultaneously. Further, the whole anti-shake lens focusing module might become inactive or abnormal when the anti-shake structure and the lens focusing structure thereof are affected by mutual resonance between a control frequency of a control integrated circuit (IC) of the module and a vibration frequency in an external environment.
For example, when the vibration frequency of a moving car, the vibration frequency of hands holding a camera for shooting pictures, the vibration frequency of a lens focusing structure during focusing, and the vibration frequency of an anti-shake structure during image correction exist at the same time, a resonant mode might occur when these four vibration frequencies are close to one another. Such resonant mode would prevent the whole anti-shake lens focusing module form operating normally to even cause failure thereof.
Since the resonant mode obviously has serious adverse influence on the operation of the whole anti-shake lens focusing module, it is necessary to suppress such resonant mode for the anti-shake lens focusing module to operate normally. It is therefore tried by the inventor to develop a method and a structure for suppressing resonance in an anti-shake lens focusing module by providing a shock-absorbing material at proper positions in a lens focusing structure and an anti-shake structure of the anti-shake lens focusing module to suppress any resonance possibly occurred therein.